Dental articles have been bonded to tooth structures for a wide variety of treatment regimens including, for example, orthodontic treatment. Orthodontic treatment involves movement of malpositioned teeth to orthodontically correct positions. Tiny orthodontic appliances known as brackets are connected to exterior surfaces of the patient's teeth, and an archwire is placed in a slot of each bracket. The archwire forms a track to guide movement of the teeth to desired positions for correct occlusion. End sections of the archwire are often received in appliances known as buccal tubes that are fixed to the patient's molar teeth. In recent years it has become common practice to use adhesives to bond orthodontic appliances to the surface of the tooth, using either direct or indirect methods. A variety of adhesives are available to the practitioner for bonding brackets to tooth surfaces, and many offer excellent bond strengths. High bond strengths are desirable for maintaining adhesion of the bracket to the tooth surface over the duration of the treatment process, which can typically be two years or more.
The use of a bonding method can typically require, among other steps, placing an amount of adhesive on a bracket or using a bracket having the adhesive precoated thereon, applying the bracket to the desired tooth structure, positioning the bracket to the desired location on the tooth, pressing the bracket to exude excess adhesive and achieve the clinically optimum location of the bracket, and removing excess adhesive. Conventional orthodontic adhesives are typically highly filled, which results in an adhesive with a white or tooth color. It is desirable that a sufficient but not an excess amount of adhesive is used to bond the bracket to the tooth structure. Excess adhesive on the tooth structure can eventually be a site for bacteria accumulation and/or staining from food or drink. Because orthodontic treatment can last from 18 to 36 months or more, bacteria accumulation can damage the tooth structure and may lead to discoloration of the adhesive, both of which are undesirable. Identifying and removing excess adhesive from tooth structure can be difficult if there is similarity in the adhesive color and the tooth color, i.e., due to a lack of a contrasting color in the adhesive. Color-changing adhesives that have an initial color that contrasts with the tooth structure have aided practitioners in the identification of excess adhesive. However, removal of the excess adhesive is typically still required.
New adhesives and methods are needed that offer satisfactory adhesion of a dental article to a tooth structure and simplify the removal of excess adhesive, if desired, upon application of the dental article to the tooth structure.